Consuming a can of Diet Coke every day could increase your risk of heart attacks, says science.
Scientists believe artificial sweeteners, which are also added to yogurt, granola and ketchup, are to blame.
Experts found that people who consume just 78 mg per day, similar to half a can of diet soda, are up to a tenth more likely to have a heart attack.
The study found that they were one-fifth more likely to have a stroke.
In an open warning to the public, French scientists concluded that they should not be considered a safe alternative to sugar.
The decade-long study of 100,000 people, published in the British Medical Journal, adds to a growing body of evidence suggesting sweeteners can be harmful to health.
However, independent experts warn that the link between sugar substitutes and heart problems is being overstated – while the well-known dangers of sugar itself are clear.
They said it was not possible to come to a conclusion about artificial sweeteners without larger and longer-term studies.
A team of French researchers studied the eating habits of more than 100,000 people, including the amount of the food additive in their diets. The results, published in the British Medical Journal, show that those who consume the most – the equivalent of half a can of a diet drink a day – are a tenth more likely to have heart disease
Researchers at France’s National Institute for Health and Medical Research in Paris looked at nutritional data from 103,388 people, including everything they ate over a 24-hour period. The chart shows how much each artificial sweetener contributed to the average person’s intake of the food additive. Aspartame accounted for more than half of the artificial sugars in the average person’s diet, while sucralose accounted for a tenth of the intake
Analysis of the dietary data found that diet soft drinks contributed half of a person’s artificial sugar intake, while tabletop sweeteners accounted for 30 percent of the intake, and artificially sweetened dairy products added just under a tenth the artificial sugars to a person’s diet
Artificial sweeteners are a key ingredient in thousands of food and beverage products, with manufacturers using them to release low-calorie or zero-calorie versions.
Dozens of studies have found a link between artificial sweeteners and weight gain.
Other research has linked overconsumption to high blood pressure and inflammation, which are themselves linked to a variety of medical problems.
So far, however, evidence on whether the food additive is behind diseases such as cardiovascular disease has been mixed.
To get to the bottom of this, researchers at France’s National Institute for Health and Medical Research looked at data from 103,388 people.
The participants, who were on average 42 years old, logged everything they had eaten for three days.
This meant that consumption of artificial sweeteners could be broken down by product – including beverages, tabletop sweeteners and dairy – and by type, such as aspartame, acesulfame and sucralose.
The team then compared this to medical records to look for a link to heart attacks and strokes.
The results showed that 37 percent of the group included the food additive in their diets, with the average daily intake being 42.5mg – about a single packet of tabletop sweetener or 100ml of a diet drink.
Those who consumed artificial sweeteners tended to be younger and fatter than those who didn’t.
They were also more likely to smoke, be less active, diet, and eat more salt, red and processed meat, dairy, and diet drinks.
All factors except being younger are thought to increase the rise in heart problems, which may have skewed the results.
However, the experts said they took this into account.
During the nine-year study, there were 1,502 heart attacks, strokes, cases of angina – chest pain caused by reduced blood flow to the heart – and angioplasty – a procedure to widen blocked arteries.
The team found that those who consumed the most artificial sweeteners were nine percent more likely to have cardiovascular disease.
The biggest consumers of artificial sweeteners had 77.6 mg per day – the equivalent of 180 ml of fizzy drinks.
This group was also 18 percent more likely to have cerebrovascular disease — conditions that affect blood flow to the brain, such as a stroke.
Aspartame, found in sugar-free drinks, ice cream and salad dressing, has been linked to the greatest risk of stroke.
The researchers admitted that their study was an observational study, which does not prove that artificial sweeteners increase the risk of cardiovascular problems.
However, they note that the study used “accurate” and “high-quality” data.
The team wrote in the journal that there appeared to be “no benefit” to heart health in swapping sugar for artificial sweeteners.
They said: “The results suggest that artificial sweeteners may be a modifiable risk factor for cardiovascular disease prevention.
“The results show that these food additives, which are consumed by millions of people every day and are found in thousands of foods and beverages, should not be considered a healthy and safe alternative to sugar, in line with the current position of several health authorities.”
However, experts pointed out shortcomings in the conclusions.
Professor Naveed Sattar, a cardiovascular disease expert at the University of Glasgow, warned of the “huge disparity” in health between those who consume the food additives and those who don’t, meaning it’s impossible to determine what role they play.
He said the researchers “far too strongly” suggested that artificial sweeteners might be behind poor heart health when their observational evidence was “weak and possibly flawed”.
Studies looking at the effects of artificial sweeteners on health have been “conflicting” and it is not possible to reach a conclusion without a long-term and large randomized study, Professor Sattar added.
Proponents argue that replacing sugar with sweeteners reduces calorie intake, controls blood sugar levels, and prevents tooth decay.
However, studies have shown that sweeteners stimulate appetite and can therefore potentially increase the risk of weight gain and obesity.
And the same team of French researchers working on behalf of President Emmanuel Macron’s government found earlier this year that sweeteners may increase cancer risk.
They monitored the nutrition and health of 100,000 people over eight years. Those who regularly consumed artificial sweeteners were 13 percent more likely to be diagnosed with cancer.
However, both Cancer Research UK and the US National Cancer Institute have stated that there is no evidence that sweeteners cause cancer.
